An amelanotic malignant melanoma indegenous to hamsters, has been grown is serial transplants in the rabbit eye (Greene tumor). We have been able to transplant this tumor with 90% successful takes in the subchoroidal space of rabbits. This was done without immunosuppression and with a technique similar to that used in the cyclodialysis procedure in ocular surgery. These tumor implants imitate in initial appearance classical choroidal tumors in man. They differ in a number of ways, including consistent lack of pigment and a speed of growth sufficient to cause the tumor to occupy most of the eye within four weeks of implantation. In the early phases, however, they can be clearly established as successful tumor takes by indirect ophthalmoscopy. The tumor at this time and in this location is a suitable experimental model for development of methods of positive identification of tumors, and for pathological studies of the effect of treatment methods such as cryodiathermy. The speed of growth of the tumor presents a stringent test of a treatment method. The report of the method of introduction of the tumor is shortly to be published and a copy of the manuscript is enclosed (1). The proposal is for work in the two areas mentioned below: 1. Further development of a detection technique for posterior ocular melanomas with anhydrotetracycline fluorescence and differential filtration to neutralize the effect of lens fluorescence interference, using the experimental posterior melanoma, with histological control. 2. Cryogenic destruction of small established melanomas by transconjunctival application with histological studies at various intervals following treatment; development of treatment schedules for resistive or large lesions; exploration of use of transvitreal cryodiathermy under ophthalmoscopic control.